The present invention relates generally to privacy systems and methods, and more particularly, to improved chaotic privacy systems and methods.
Traditionally privacy for analog signals is established by digitizing the signals, then encrypting bits of the signal with a secure algorithm, which then generates a digital signal for transmission, or the digital signal is reconverted back to an analog signal. The sampling process is error prone with sampling error, quantizing error and losses due to a bandlimited channel. If the original analog signal is desired, then the received digital signal could be passed through a digital-to-analog converter to recover the analog signal.
Examples of this process include secure speech and secure video. For analog signals of high bandwidth, the sampling process is even more error prone due to technology limitations of analog-to-digital converters. For example, a 4 GHz bandwidth with a 10 giga-sample per second sample rate, each sample with 8 bits per sample, requires a transmission bit rate of 80 giga-bits per second. Neither the analog-to-digital conversion nor the free space transmission bandwidth are possible with currently-available technology.
Analog privacy involves information secrecy where the information is concealed by a cipher or a code. The existence of a message is not hidden, only its information content. An unintended receiver is assumed to have the required equipment necessary to intercept and record the transmitted signal. The interceptor may even know the structure of the transmitter and receiver.
In Shannon Secrecy, the probability density of transmitted signal is independent from the information signal probability density. One way to achieve this independence is to cause the transmitted signal to have nearly an nth order uniform density distribution. The inverse function, which recovers the information, would require a key parameter without which no information can be recovered.
The other traditional approach for protecting analog signals is spread spectrum and/or frequency hopping techniques. The spread spectrum techniques use a pseudorandom noise generator with a reproducible number sequence in the receiver. These techniques have a pseudo random repetition period, which can be used to break the disguised signal.
It is therefore an objective of the present invention to provide for chaotic privacy systems and methods that protect analog signals and improve upon the above-discussed techniques.